Wireless communications systems that use certain unlicensed frequency bands for transmission have proliferated. For example, Wi-Fi networks that operate using unlicensed frequency bands in the 2.4 or 5.0 GHz frequency range are now used by a majority of businesses and public/private organizations as wireless local area networks (WLANs).
Because there are no restrictions on the types of systems that may use these unlicensed frequency bands, this proliferation of systems has resulted in greater potential for interference to exist in the RF environments of the wireless systems that operate in these frequency bands. As one example of potential for interference in unlicensed frequency bands, service providers have implemented Long Term Evolution (LTE) networks that may transmit on what are known as the LTE-Unlicensed (LTE-U) channels. The LTE-U channels are in the same 5 MHZ frequency bands that are specified by IEEE 802.11 for use by Wi-Fi networks. Because the LTE systems transmit at high power levels and may acquire and hold the 5 MHZ channels for long periods of time, the LTE networks may cause severe interference on the Wi-Fi networks. For example, Wi-Fi networks currently operate using a feature that backs off packet transmission frequency by a transmitting device during the presence of interference to avoid errors in transmissions. The persistent interference from an LTE system transmitting in the LTE-U band may cause a Wi-Fi device to back off packet transmissions and remain backed off so that the transmissions are substantially interfered with and data throughput becomes unacceptable.
In general, the increasing use of systems and networks such as business WLANs, public hotspots, home media devices, LTE networks using the LTE-U band, and other wireless devices and networks, has potential to increase interference levels and interfere with transmission in co-existing wireless networks that use the same frequency bands or adjacent frequency bands.